Objective-C is a thin layer on top of C, and is a "strict superset" of C, meaning that it is possible to compile any C program with an Objective-C compiler, and to freely include C language code within an Objective-C class.
Objective-C derives its object syntax from Smalltalk.
All of the syntax for non-object-oriented operations (including primitive variables, pre-processing, expressions, function declarations, and function calls) is identical to that of C, while the syntax for object-oriented features is an implementation of Smalltalk-style messaging.

You can find more information about the language and its history here.

I've been coding in Objective-C ever since the first release of the iOS SDK, back in the old manual memory management days! It's been a fun ride and I'm excited to share and help people to write great apps!